The RV Forum Community

I have an older bus conversion. It has a 24v system for the batteries. I have only the 2 batteries charged by a 350amp alternator for starting the bus, no house battery bank. I have a 3600w/5000m peak inverter that came with the bus, but was not wired up. Can I hook the Inverter directly to the batteries. Wire size and fuse size recommendations would be helpful. I was told the 0 gauge wire with a 350a fuse would be fine, less than 3' of wire being used. No boondocking, the inverter would only be used while on the road to power one ac unit. Once we are at our destination we will plug into shore power. I am setting it up so that I have to physically unplug from the inverter to plug into shore power. One other question, does the dc negative side have to been run back to the battery or can it be ground to the bus chassis. I've worked on high power audio systems and this is a common practice to limit the amount of wire that has to be used. Hopefully I explained what I'm wanting to do properly. Thanks in advance for any advice and help.

At 24 volts input, you'll pull about 150 amps at 3600 watts. A 350 amp catastrophic fuse will work fine - you don't want it to blow except in the event of a catastrophic short.

Everything you said sounds good, but I'd run a second short lead directly back to the batteries. Connections are the biggest trouble spots at high currents and running the ground wire directly eliminates at least two junctions going to and from the chassis (and any that may be in between).

How are you going to connect the wires to the batteries? You'll want lots of contact area, not just a spade lug tied to a battery post. You'll also want to look at the size of wire going to the alternator along with it's connections. It will have to carry at least as much current as the inverter is drawing if you're powering a continuous load.

You could likely get by with ZERO but I'd use 2/0 or 4/0 GA wire myself.. (Welder wire) I like to go big on the wire.

Within the limit of reasonable.. You can not go TOO big, 2/0 is likely about the point of diminishing returns but 4/0 is what I use on a 2000 watt 12 volt b ox.. yours is nearly 2x as watts, but also 2x the volts so 4/0 would be my choice there too.

The wire I'm using and the existing cables are 0 gauge. I wasn't going to use any connectors except on the fuse block. The block the 2 twelve volt batteries connect to has a large bolt and washers that will easily allow me to unbraid the wire in halves, wrap it around the bolt and sandwich it in between the 2 large washers that are there. That's pretty much what you are doing with a connector, smashing it down enough to secure the wire/cable Was hoping to eliminate losses thru connectors with a direct connection, I normally try use as few connector as possible. There are two blocks one 24v+ and 24v- that are easily accessible on the wall off the battery compartment, the run to a 24v on/off switch in the adjacent storage area. That is the way the original inverter was hooked up, the previous inverter was about the same size as the new one I'm hooking up. So I'm assuming all the existing cable is sufficient to handle everything. John, I agree with you on the wiring, bigger is better. But the way I understood it was 12v needs way bigger wiring. I looked thru a lot of install kits and 0 gauge seem to be the most commonly used for my particular application , especially considering the length of the wire is under 3 ft, more like 2 ft. Thanks for the input ya'll